2-Methylpiperazine → rac-1-Ethyl-6-fluoro-1,4-dihydro-7-(3-methyl-1-piperazinyl)-4-oxo-3-quinoline-carboxylic acid monosodium salt

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Reaction Steps

A mixture of 7-chloro-1-ethyl-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid [J. Med. Chem., 23, 1358 (1980)] (0.52 g, 2 mmol) and 2-methylpiperazine (0.8 g, 8 mmol) was heated at 175° for 5 hours. The residue was dissolved in ethylacetate (10 mL) and chloroform (10 mL), and a solution of sodium-2-ethyl- hexanoate (0.33 g, 2 mmol) in ethyl acetate (20 mL) was added. The mixture was stirred for 30 minutes and the precipitate was collected. The crude product was purified by preparative liquid chromatography (C-18 reverse phase, gradient 0-40% acetonitrile in water) to give a pale yellow lyophilized solid (0.5 g, 75% yield).

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